Low friction latch bolt and hinge guide



March 9, 1965 F. J. RUSSELL 3,172,691

LOW FRICTION LATCH BOLT AND HINGE GUIDE Filed Feb. 6, 1963 2Sheets-Sheet 1 so A &4 g, F E '1. RUSSELL 43 INVENTOR. 44 24 49 a 40 5 14 5 7 BY ATTcQNEVS March 9, 1965 F. J. RUSSELL 3,172,591

LOW FRICTION LATCH BOLT AND HINGE GUIDE Filed Feb. 6, 1963 2Sheets-Sheet 2 F251: J. ZZusssu- INVENTOR.

ATTORHBVS United States Patent 3,172,691 LOW FRICTION LATCH BOLT ANDHINGE GUIDE Fred J. Russell, 3800 Don Felipe Drive,

Los Angeles, Calif. Filed Feb. 6, 1963, Ser. No. 256,697 6 Claims. (Cl.292-163) The invention relates to door locks and has special referenceto a latch assembly of a door lock. In the present instance, the type oflatch assembly involved is one wherein the latch bolt protrudes for aconsiderable distance outwardly from the latch face and into engagementwith the customary strike plate, as is frequently the case where latchassemblies, of the kind under consideration, are used on a pair of firedoors.

A common construction for a latch assembly is one which provides a metalfront plate having an opening adapted to receive the latch bolt which islikewise made of metal and to provide for it a sliding fit as the latchbolt is reciprocated when the door is opened and closed. The commonconstruction thus made reference to require a metal-to-netal engagementof the latch bolt with the front plate hole, and engagement of this kindresults in considerable wear on one or both parts. Also, in the absenceof lubrication, and especially where there is a relatively long throwfor the latch bolt, considerable frictional resistance is built up.Although frictional resistance could be reduced by using grease for thefrictionally engaging parts, this expedient is objectionable for doorhardware, since the grease is very apt to soil the hands or clothing ofa person who has access to the door on which the latch assembly ismounted.

Further still and in view of the wear which takes place as a result ofmetal-to-metal engagement of the parts,

the parts get loose and cause rattling of the parts when in use, andsometimes there is a feeling of lack of security in the closure. Whereconsiderable throw is needed for the latch bolt, that is to say, undercircumstances where the latch bolt protrudes outwardly from the frontplate at a distance greater than usual, difficulty is experienced indepressing the latch bolt as it strikes the lip of the strike plate. Toclose the door either requires slamming the door closed withconsiderable force or the employment of some auxiliary agency to startthe depressing of the latch bolt before full cam action takes place inorder to minimize wear and damage to the parts.

It is therefore among the objects of the invention to provide a new andimproved low friction guide for a latch bolt so as to minimize wear to asubstantial degree over that heretofore experienced.

Another object of the invention is to provide in a latch bolt action notonly a low friction guide for eliminating wear of the parts, but whichalso is of such construction as to provide an advantageous pivot pointfor an auxiliary latch bolt retracting mechanism in the form of aretractor lever.

Still another object of the invention is to provide a new and improvedretractor lever device for starting the retraction of a latch bolt, bothwhen the door is closing and when the latch bolt tailpiece is retractingby operation of an appropriate retract mechanism.

Still another object of the invention is to provide a new and improvedlow friction latch bolt guide and an accompanying retractor lever whichis simple and positive in its assembly and of such construction thatfabrication and assembly can be accomplished with very little additionalcost in either materials or assembly time.

Still further among the objects of the invention is to provide amultiple purpose low friction guide for a latch bolt which serves as alow friction guide for latch bolt reciprocating movement, as a lowfriction mounting for an auxiliary retractor lever mechanism, and alsoas a washer to improve the engagement of the latch bolt casing with thecustomary front plate.

With these and other objects in view, the invention consists in theconstruction, arrangement and combination of the various parts of thedevice, whereby the objects contemplated are attained, as hereinafterset forth, pointed out in the appended claims and illustrated in theaccompanying drawings.

In the drawings:

FIGURE 1 is a longitudinal view, partially broken away, showing thestrike camming side of a latch assembly incorporating the invention.

FIGURE 2 is a cross sectional view on the line 22 of FIGURE 1.

FIGURE 3 is a longitudinal sectional view of the latch assembly taken onthe line 3-3 of FIGURE 1.

FIGURE 4 is a fragmentary longitudinal sectional view similar to FIGURE3, but showing the relative position of the parts at a door closingposition slightly advanced from the position of FIGURE 3.

FIGURE 5 is a longitudinal sectional view similar to FIGURES 3 and 4,but showing the latch bolt in the position it would occupy immediatelyprior to a full closing of the door.

FIGURE 6 is a front elevational view of the latch assembly.

FIGURE 7 is an end face perspective view of the low friction latch boltand hinge guide wherein significant parts of the guide are mounted in anassembly preparatory to incorporation in the device.

In a chosen embodiment of the invention incorporating an example whichis illustrative of the invention, there is provided a casing 10 adaptedto be secured -to a front plate 11 by employment of a fastening plate 12so that a latch assembly featuring in part a latch bolt 13 isreciprocatively mounted in position. As shown in FIG- URE 2, the latchassembly is designed to be mounted in the edge of a door 14, a fragmentof which is shown in FIGURE 2, where it is adapted to cooperate with astrike plate as suggested in FIGURE 3, a portion of the strike plate 15being shown mounted upon a fragment of door frame 16.

Following substantially coventional construction, the front plate 11 isprovided with a hole 17 through which a latch bolt 13 passes. In orderto hold the casing 10 and front plate 11 in assembled relationship, thecasing is provided with an annular flange 19 which is engaged by thefastening plate 12. The front plate 11 is held in engagement with thefastening plate 12 by bosses (not shown) which extend from the back sideof the front plate 11 through holes (not shown) in the fastening plate12 and then are spun or staked together. Spacing flanges 22 on oppositeedges of the fastening plate 12 bear against the rear face of the frontplate 11, and provide a slight space between the two. A shoulder portion23' of the latch bolt 13 lies in the area behind the front plate 11, sothat the latch bolt cannot be pushed out of the casing, once the frontplate 11 and the fastening plate 12 are staked or spun together.

More particularly, the latch bolt 13 on the side normally facing thecurved lip of the strike 15 has a curved cam face 23 and a shortstraight section 24 where the cam face 23 joins a body portion 25, thebody portion being that portion of the latch bolt 13 which always lieswithin the casing 10. On the side of the latch bolt 13 opposite thecurved cam face 23 side is a flat wall 26, the flat wall 26 beinginstrumental in preventing rotation of the latch bolt in its mounting.

At the inner end of the body portion 25 is an opening 7 in which islocated a spring 28. A smaller opening 29, at the inner end of theopening 27, provides a shoulder 3 upon which the outer end of the spring28 is kept. A peg 31 mounted by appropriate means on a bottom wall 32 ofthe casing 10 serves as a guide for the spring 28. On theopposite sideof the casing within a chamber 33 inside the casing, is a second guidepeg 34 which may be similarly mounted by conventional means on thebottom wall 32. The guide peg 34 extends through a milled slot 35 in thebody portion 25 of the latch bolt 13. The guide peg 34 serves to guidethe latch bolt during its movement, the guiding being furtherenhanced-by the peg 31 when the latch bolt 13 moves far enough sothatthe peg 31 passes into the opening 29. Inside of the bottom wall 32 is abracket 36 which is made use of in a conventional fashion when the latchassembly is mounted upon one of the usual types of frames with which alatch assembly of this type is customarily used.

A substantial portion of the special subject matter here underconsideration is embodied in a combined low friction latch bolt guideand hinge mounting member indicated generally by the reference character40 and shown in perspective view in FIGURE 7. The member 40 includesinpart a flat area 41, the outer portion of which is substantiallyannular and is interposed between the inside face of the front plate 11and the outer perimeter of the flange 19. Hence, this flat area 41serves in part as a washer for the connection between the casing 10,fastening plate 12, and the front plate 11, as well as serving partiallyto enclose the corresponding end, namely, the outer end of the casing 19and its chamber 33.

It will also be noted that the flat area 41 is provided with an aperture43 which has in general the same shape and size as the outside perimeterof the latch bolt 13 and further that it provides a sliding fit for thelatch bolt 13. A flange 44 protrudes outwardly from the outer face ofthe fiat area 41 so as to extend into the hole 17 in the front'plate 11and, in effect, to provide a'liner for the hole 17.

' On the inside face of the fiat area 41 are a pair of hinge brackets45and 46 for pivotally mounting a retractor lever '47 for actuation of thelatch bolt 13. A partially cylindrical boss 48 forming part of theretractor lever 47 fits between the hinge brackets 45 and 46 wherein itis pivotally retained by employment of a pin 49.

So that the retractor lever 47 may be able to cooperate with the latchbolt 13, the latch bolt 13 is provided with a recess'50 on its curvedcam face 23 side which extends entirely through the protruding outerportion of the latch bolt 13 and partially into the interior as shownadvantageously in FIGURES 3, 4, and 5, the breadth of the recess 50being slightly greater than the breadth of the retractor lever 47 so asto provide ample freedom of movement of the retractor lever 47.

Within the recess 50 of the latch bolt 13 are located two stationarilymounted pins 51 and 52 which, in effect, may be described as drivenconfigurations. On an arcuate face ss'or the retractor lever 47 arecomplementary semi- -cylindrical recesses 54 and 54 which are designedto re ceive respectively the pins 51. and 52 at different cycles of Ioperation, as shown in FIGURES 3, 4, and 5.

Located within the chamber 33 is a tailpiece 55 which extends inwardlythrough the chamber 33 and then through a hole 56 in the bracket 36 andthence to a location where a cross bar 57 on the tailpiece 55 isprovided for the purpose of making an appropriate attachment to aconventional latch retract mechanism. At its outer end, the tailpieceextends into the slot 35 in the inner body portion 25 of the latch bolt13 and at that location is connected to a link 58 by means of a pin 59.A slot 60 in the link 58 in which the pin 59 is located is elongated inorder to provide a desirable lost motion connection, as shown, betweenthe tailpiece 5S and the link 58 as shown. The other end of the link 58is pivotally secured to the retractor lever 47 within a recess 61 in theretractor lever 47 by means of a pin 62. In initial extended position,the latch bolt 13 and attached parts of the device have the relationshipas shown in FIGURE 3. In this relationship,

the spring 28 has pushed the latch bolt 13 as far outwardly as it cango, namely, until the shoulder portion 23' abuts against the adjacentface on the inner side of a thickened portion 42 of the latch bolt guideand hinge mounting member 40. Since the latch bolt 13 is forcedoutwardly, as shown, so also will'be the hinge brackets 45 and 46 andaccordingly the pivotal mounting of the retractor lever 47. At the sametime the pin 52 within the recess 50 of the latch bolt 13 will cause theretractor lever 47 to be rotated in a counter-clockwise direction asviewed in FI URE 3 to the maximum extent of its movement, so that astrike edge 63 of the retractor lever '47 will protrude outwardly beyondthe'surface of the cam face 23 of the latch bolt 13, as shown in FIGURE3.

When the door 14 in which the latch assembly is mounted is to be closed,it will swing so that a strike edge 63 of the retractor lever 47 willhit the curved lip of the strike plate 15. As movement continues, theparts will pass from the relative positions shown in FIGURE 3 to therelative positions shown in FIGURE 4. This happens because the retractorlever 47 is rotated slightly in a clock. wise direction as viewed inFIGURES 3 and 4. When this is occurring, the lost motion provided by theslot 60 is taken up, and, thereafter, the wall of the recess 54' willengage with the pin 52 and action of the retractor lever 47 will in thatmanner cause partial withdrawal of the latch bolt 13 to the positionshown in FIGURE 4.

After the latch bolt 13 and the retractor lever 47 have reached thepositions shown in FIGURE 4, the next fitcrement of movement of thelatch bolt 13 as the door continues to close will be for the cam face 23to engage the curved lip of the strike plate 15. From here on,retraction of the latch bolt 13 will be accomplished by this actionuntil the parts assume the relationship shown in FIGURE 5. As thismovement occurs and the semicylindrical recess 54 becomes disengagedfrom the pin 52, the semicylindrical recess 54 will nextbecome' engagedwith the pin 51 and the retractor lever 47 will continue to beretracted, but this time because of being pulled into retractedpositions by action of the latch bolt 13. From here as the doorcontinues to be closed, the latch bolt 13 will move until the latch bolt13 coincides with the customary conventional opening (not shown) in thestrike plate 15, at which point, by action of the spring 28 the iatchbolt 13 will be extended to temporarily latch the door in closedposition.

From the description of the parts given, it will be noted that the latchbolt guide and hinge mounting member 40 provides the low frictionelement of the combination. It is advantageously constructed of anonmetallic plastic material such as a synthetic plastic resin, typicalcommercial examples of which are nylon and Delrin. These materials havevery low friction surface characteristics, and hence, there is a verylow friction contact between any relatively sliding portions of thedevice. This means that there is a low friction engagement between theoutside circumference of the latch bolt 13 and the flange 44,Simultaneously, the member 40 serves as a pivot hinge point for theretractor lever 47.

When, as is the case on some occasions, the retractor lever 47 is madeof low friction material, there also is a low friction engagementbetween the strike edge 63 of the retractor lever 47 and the strikeplate 15.

While the invention has herein been shown and described in What isconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of theinvention which is not to be limited to the details disclosed herein butis to be accorded the full scope of the claims so as to embrace any andall equivalent devices.

Having described the invention, what is claimed as new in support ofLetters Patent is:

1. In a latch assembly for a lock, a casing, a latch bolt reciprocatablymounted in said casing, a low friction guide for said latch boltcomprising a member of low friction materialhaving one portion thereofretained by said casing, another portion thereof in sliding engagementwith said latch bolt and a bracket portion thereof on the side of saidmember facing said casing, and a latch bolt retractor lever pivotallymounted on said bracket portion and adapted to reciprocate said latchbolt in said casing.

2. In a latch assembly for a lock, a casing, a latch bolt reciprocatablymounted in said casing, and a guide member of low friction materialhaving one portion thereof retained by said casing, another portionthereof in sliding engagement with said latch bolt and a bracket portionon the face thereof facing said casing, said guide member including aretractor lever comprising a body, a pivot connection on one side ofsaid body pivotally connecting said body to said bracket portion on anaxis spaced from and in angular relationship to the axis of movement ofsaid latch bolt, a strike face on said body adjacent the pivotconnection, and drive means between said retractor lever and said latchbolt adapted to transfer motion said retractor lever to the latch boltduring movement of the latch bolt through a door closing cycle;

3. In a latch assembly for lock, a casing, a latch bolt reciprocatablymounted in said casing, and a guide member of low friction materialhaving one portion thereof retained by said casing and another portionthereof in sliding engagement with said latch bolt, said guide memberincluding a retractor lever comprising a body, a pivot connection on oneside of said body pivotally connecting said body to said guide member, astrike face on said body adjacent the pivot connection, and drive meansbetween said retractor lever and said latch bolt adapted to transfermotion from said retractor lever to the latch bolt during movement ofthe latch bolt through a door closing cycle, said drive means comprisinga drive section facing said latch bolt and a plurality of mutuallyengaging drive configurations respectively on said drive section and onsaid latch bolt adapted to engage progressively during said door closingcycle.

4. In a latch assembly for a look, a casing, a latch bolt reciprocatablymounted in said casing, a low friction guide for said latch boltcomprising a member of low friction material having one portion thereofretained by said casing and another portion thereof in slidingengagement with said latch bolt, and a latch bolt retractor leverpivotally mounted on said low friction guide, said retractor levercomprising a member of low friction material having a strike face on oneside and having a driving engagement with said latch bolt adapted toreciprocate said latch bolt in said casing.

5. In a latch assembly for a lock, a casing, a latch bolt reciprocatablymounted in said casing, and a guide assembly comprising a guide memberof low friction material having one portion thereof retained by saidcasing and another portion thereof in sliding engagement with said latchbolt, said guide assembly including a retractor lever comprising a body,a pivot connection on one side of said body pivotally connecting saidbody to said guide member, a strike face on said body adjacent the pivotconnection, said guide member having a location overlying the adjacentinside area of said strike face, and drive means between said retractorlever and said latch bolt adapted to transfer motion from said retractorlever to the latch bolt during movement of the latch bolt through a doorclosing cycle, said latch bolt having a portion thereof in engagementwith said guide member in extended position of said latch bolt.

6. In a latch bolt device a casing having inner and outer ends and achamber therein, a reciprocating latch bolt assembly in said chambercomprising a latch bolt head at the outer end having a strike face sideand a side opposite said strike face side, a front plate attached to thecasing in position overyling the outer end of said casing, said frontplate having an opening therein for said latch bolt head, and a guideassembly comprising a guide member of low friction material positionedadjacent the inside face of said front plate, said guide member havingan opening therein smaller than the opening in said front plate andconforming substantially to the exterior shape of said latch bolt head,said guide assembly including a hinge guide of low friction materialcomprising a body, a pivot connection on one side of said body pivotallyconnecting said body to said guide, a strike face on said body adjacentthe pivot connection, a drive face on said body on the side oppositesaid pivot connection, a plurality of drive configurations at spacedlocations on said drive face and complementary driven configurations onsaid latch bolt head adapted to transfer motion from said hinge guide tothe latch bolt head during movement of the latch bolt device through adoor closing cycle.

References Cited by the Examiner UNITED STATES PATENTS 1,514,528 11/24Hurd 292---192 2,107,299 2/ 3 8 Kilpatrick 292192 2,812,204 11/ 57Squire. 2,841,974 7/58 Hensel.

ALBERT H. KAMPE, Primary Examiner.

M. H. WOOD, 1a., Examiner.

1. IN A LATCH ASSEMBLY FOR A LOCK, A CASING, A LATCH BOLT RECIPROCATABLYMOUNTED IN SAID CASING, A LOW FRICTION GUIDE FOR SAID LATCH BOLTCOMPRISING A MEMBER OF LOW FRICITON MATERIAL HAVING ONE PORTION THEREOFRETAINED BY SAID CASING, ANOTHER PORTION THEREOF IN SLIDING ENGAGEMENTWITH SAID LATCH BOLT AND A BRACKET PORTION THEREOF ON THE SIDE OF SAIDMEMBER FACING SAID CASING, AND A LATCH BOLT RETRACTOR LEVER PIVOTALLYMOUNTED ON SAID BRACKET PORTION AND ADAPTED TO RECIPROCATE SAID LATCHBOLT IN SAID CASING.